The subject matter disclosed herein relates to variable frequency drives (VFDs) for driving electric machines, and more specifically to systems and methods for active damping of a motor used with electric submersible pumps (ESPs) in oil and gas applications.
In typical oil and gas drilling applications a well bore is drilled to reach a reservoir. The well bore may include multiple changes in direction and may have sections that are vertical, slanted, or horizontal. A well bore casing is inserted into the well bore to provide structure and support for the well bore. The oil, gas, or other fluid deposit is then pumped out of the reservoir, through the well bore casing, and to the surface, where it is collected. One way to pump the fluid from the reservoir to the surface is with an electrical submersible pump (ESP), which is driven by an electric motor (e.g., induction motor or a permanent magnet motor) in the well bore casing.
A variety of components may be used to receive power from a power source, filter, convert and/or transform the power, and then drive the electric motor. For example, a variable frequency drive (VFD) may receive power from a power source (e.g., utility grid, batteries, a generator, etc.). The power may then pass through a filter and a step up transformer to generate a stepped up voltage, and the stepped up voltage may be provided to the electric motor via a cable that passes through the well bore. As noted above, the electric motor may be an induction motor or a permanent magnet motor, and may be utilized within the well bore casing to drive the ESP. In some situations, it may be desirable to utilize a permanent magnet motor instead of an induction motor. However, it may be difficult to control and drive a permanent magnet motor in an efficient and stable manner.